[Another new etiology of vertebral artery insufficiency--a case of dynamic entrapment of the vertebral artery by the cervical nerve].

In the etiology of vertebral artery insufficiency, cervical spondylosis with uncal osteophyte, Power's syndrome, A-V malformation and atheromatous narrowing have been recognized. We recently experienced a patient with episodic vertigo and hyposthenia of the left side of the body on rotational movement of the neck. On surgical exploration of the atlanto-axial area of the vertebral artery where dynamic constriction of the artery could be observed by angiography, we found that the right vertebral artery was entrapped and constricted by the anterior branch of the second cervical nerve with fibrous adhesion after injury. With the release and resection of the injured nerve, the patient became free of any vertigo or hyposthenia. Although this kind of etiology involving entrapment-constriction of the vertebral artery by the cervical nerve after trauma has not been reported at all in the literature, we should always keep this in mind when dealing with patients with cervical vertigo after trauma.